Answer:
<em>293.99 g </em>
OR
<em>0.293 Kg</em>
Explanation:
Given data:
Lattice energy of Potassium nitrate (KNO3) = -163.8 kcal/mol
Heat of hydration of KNO3 = -155.5 kcal/mol
Heat to absorb by KNO3 = 101kJ
To find:
Mass of KNO3 to dissolve in water = ?
Solution:
Heat of solution = Hydration energy - Lattice energy
= -155.5 -(-163.8)
= 8.3 kcal/mol
We already know,
1 kcal/mol = 4.184 kJ/mole
Therefore,
= 4.184 kJ/mol x 8.3 kcal/mol
= 34.73 kJ/mol
Now, 34.73 kJ of heat is absorbed when 1 mole of KNO3 is dissolved in water.
For 101 kJ of heat would be
= 101/34.73
= 2.908 moles of KNO3
Molar mass of KNO3 = 101.1 g/mole
Mass of KNO3 = Molar mass x moles
= 101.1 g/mole x 2.908
= 293.99 g
= 0.293 kg
<em><u>293.99 g potassium nitrate has to dissolve in water to absorb 101 kJ of heat. </u></em>
Based on the data given, the molar mass of the gas is 165.5 g/mol while the molecular weight of the gas is 165.5 amu
<h3>How can molar mass of a gas be obtained from density, temperature and pressure?</h3>
The molar mass of a gas can be obtained from density, temperature and pressure using the formula below:
- molar mass = density × molar gas constant × temperature/pressure
Molar gas constant, R = R = 0.082 L.atm/mol/K.
Temperature = 150 °C = 423 K
Pressure = 785 torr = 1.033 atm
density = 4.93 g/L
molar mass of gas = 4.93 × 0.082 × 423/1.033
molar mass of gas = 165.5 g/mol
Then, molecular weight of the gas = 165.5 amu
Therefore, the molar mass of the gas is 165.5 g/mol while the molecular weight of the gas is 165.5 amu
Learn more about molar mass of a gas at: brainly.com/question/26215522
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